Apparatus for removing drilling mud from a well having a prepacked liner



p 4, 3956 c. J. COBERLY APPARATUS FOR REMOVING DRILLING MUD FROM A WELL HAVING A PREPACKED LINER S Sheets-Sheet 1 Filed June 12, 1950- /Nl/NTO/?. CLARENCE d. CUBE/FLY BY H/S HTTO-RNEYS. H1) RIF/5, K/iCH, F05 T51 5; HARP/5 7 P J 2 a Sept. 4, 1956 BERLY 2,761,514

C. J. CO APPARATUS FOR REMOVING DRILLING MUD FROM A WELL HAVING A PREPACKED LINER Filed June 12. 1950 I5 Sheets-Sheet 2 CLARENCE d. 6055/? BY H/S ATTORNEYS. HARP/s, KnscH, Fosrz/P 3=HHRRI6 W A? 4mm our p 4, 1956 c. J. COBERLY 2,761,514

APPARATUS FOR REMOVING DRILLING MUD FROM A WELL HAVING A PREPACKED LINER Filed June 12, 1950 3 Sheets-Sheet 3 //v|/./v TOR. CLARENCE d. (Sosa/av BY HIS ATTORNEYS. v HARE/5 K/ECH, F05 T/?&HA/?R/5 a N). m.

United States Patent APPARATUS FOR REMOVING DRILLING MUD FROM A WELL HAVING A PREPACKED LINER Clarence J. Coherly, Los Angeles, Calif., assignor, by mesne assignments, to Kobe, Inc., Huntington Park, Calitl, a corporation of California Application June 12, 1950, Serial No. 167,633

4 Claims. (Cl. 166-144) The present invention relates in general to apparatus for bringing in a well and, more particularly, to apparatus for removing foreign material such as drilling mud from an annulus between the well bore and a foraminous liner set in the well bore at the level of a producing formation, a primary object of the invention being to provide apparatus for removing substantially all of the drilling mud from such an annulus while preventing the drilling mud from entering the forarnina of the liner.

Although not limited thereto, the present invention is of particular utility in completing an oil well and will be described in such connection herein as a matter of convenience. in drilling an oil well by the rotary method, it is customary to circulate a heavy drilling mud downwardly through the drill pipe and upwardly through the annulus between the drill pipe and the casing, or the annulus between the drill pipe and the well bore. As is wel known in the art, such a circulation of drilling mud performs several functions, one of these being to remove from the well bore cuttings produced by the .drill bit. The drilling mud also serves as a lubricant and, since it has a relatively high density, the column of drilling mud in the well bore provides a high static pressure which holds back any oil and gas tending to enter the well bore until such time as the well is ready to be brought in. Also, the drilling mud plasters the Wall of the well bore to prevent cave-in or sanding up. It is, of course, necessary to remove the drilling mud from the well bore in order to bring in the well, as will be discussed in more detail hereinafter.

Oil and gas producing formations are usually sands having varying degrees of consolidation and varying particle sizes. For example, the degree of consolidation may range from loose sand to sandstone and the particle size may range from very fine or flour sand to coarse gravel. The thickness of the producing formation is also variable and may range from a few feet to several thousand feet. In wells having producing formations composed of relatively loose sand, there is a tendency for the sand to slulf ofi into the well bore and thus cause the well to sand up, particularly where the formation is relatively thick. In order to prevent this, it is customary to set in the well bore at the level of the producing formation a foraminous liner the foramina of which are sufiiciently small to sub stantially exclude the sand from the interior of the liner while permitting oil, gas and any other fluids forming the well fluid to enter the interior of the liner. The forarninous liner may comprise a screen casing, which is merely a casing having perforations therein, usually in the form of narrow slots. Alternatively, a prepacked gravel line: may be employed, such a liner comprising perforated inner and outer casings which are concentrically arranged and interconnected, but which are spaced apart radially to provide an annulus to receive a gravel pack, the term gravel pack covering a pack formed of particles ranging in size from fine sand to coarse gravel. The screen casing type of liner is satisfactory when the producing formation is composed of relatively large particles, but

is not feasible for fine sand since the slots must then be of such narrow width as to make manufacturing costs prohibitively high. Also, under such conditions, the slots must be so numerous, in order to provide adequate permeability, as to weaken the liner materially. With a prepacked gravel liner, on the other hand, the particle size of the gravel employed for the gravel pack may be materially larger than the effective particle size of the formation sand, e. g., ten times the effective particle size, and the prepacked gravel liner will still substantially exclude the formation sand from the interior of the liner. Consequently, with the relatively large particles employed for the gravel pack, the slots or other perforations in the inner and outer casings of the prepacked liner may be relatively large and the slots in the inner casing in particular may be relatively few in number to avoid the obections voiced above. As a matter of convenience in disclosing the present invention, it will be considered hereinafter in connection with a prepacked gravel liner, although it will be understood that it is not necessarily limited thereto.

After drilling of a well bore has been completed and a casing and liner set therein, it is necessary to remove the drilling mud employed during the drilling operation before the well can be brought in, as is well known in the art. The major portion of the drillling mud may be removed from the well bore readily in various ways, but, before the well can be brought in, it is necessary to remove substantially all of the drilling mud from the annulus between the well bore and the foraminous liner. If the formation pressure is sufficiently high, the oil and gas contained in the formation may displace the drilling mud from the annulus, but, in most instances, this is not the case and it is necessary to wash the mud from behind the liner with water, or various other suitable fluids. When this is done in accordance with prior practice, the drilling mud is forced out of the annulus through the foramina of the liner, whether such foramina be slots in a screen casing, or interstices between particles of a gravel pack. This frequently results in plugging a substantial portion of the foraminous liner with the drilling mud to render it relatively impermeable to flow of well fluid from the producing formation. Also, when the annulus is washed out in this manner, the drilling mud frequently re-enters the annulus above and below the point of washing so that it is extremely difficult to remove all of the mud.

An important object of the present invention, therefore, is to provide apparatus for removing the drilling mud from the annulus between the liner and the well bore which eliminate the foregoing disadvantages of conventional practise.

An important object is to provide a foraminous liner which is impervious to the drilling mud so that the mud cannot enter and close the foram'in'a of th liner.

More specifically, an important object is to provide a forarninous liner the foramina of which are closed by a sealing material which is insoluble in the drilling mud, i. e., in the vehicle carrying the drilling mud, but which is soluble in another fluid so that it may be dissolved out to open the foramina of the liner once the drilling mud has been removed fro-m behind the liner. A related object is to provide a sealing material for the foramin'a of the liner which is oil soluble so that it may be dissolved out by the oil from the producing formation.

An important object is to employ a sealing material in certain applications of the invention which is soluble in a solvent other than oil or water. With such a sealing material, various zones of the liner may be opened selectively by applying the solvent only to those. zones'which are to be opened. For example, it may be desirable to open only the lower end of the liner initially, particularly where the upper end of the liner may be in or near a gas cap when the well is first brought in. Opening the entire liner when the well is first brought in would, under such conditions, result in an excessive gas-oil ratio. Also, if part of the producing formation is a very tight sand, it is desirably opened first to get it cleaned out thoroughly before production is started from the more permeable parts of the formation. If the tight sand is not cleaned out while the formation pressure is high, it may never produce since the Well fluid will by-pass it when more permeable parts of the formation ar opened. Thus, the use of a sealing material requiring a special solvent permits selective opening of the liner with advantages such as those noted above.

Another object is to provide apparatus for conducting the washing fluid to the lower end of the annulus and for discharging the washing fluid and drilling mud from the upper end thereof so that the vertical Washing in the annulus takes place in an upward direction.

Another object is to provide apparatus for conducting the washing fluid into the annulus at the upper end thereof and for discharging the washing fluid and the drilling mud from the lower end thereof so that the vertical washing in the annulus takes place in a downward direction.

Another important object is to provide a liner having adjacent its respective ends inlet and outlet passages which are adapted to communicate with the annulus behind the liner to permit such vertical washing of the annulus.

Another object is to provide an apparatus including a wash pipe which is adapted to be removably connected to the liner in fluid-tight engagement therewith and in communciation with one of the aforementioned passages.

Still another important object is to provide valve means actuable by the wash pipe upon connection thereof to the liner for opening the inlet and outlet passages, and actuable by the wash pipe upon disconnection thereof from the liner for closing th inlet and outlet passages. With this construction, the well fluid in the annulus can enter the interior of the liner only through the foramina thereof once the wash pipe has been removed and the sealing material in the foramina has been dissolved out, which is another feature of the invention.

The foregoing objects and advantages of the present invention, together with other objects and advantages thereof which will become apparent, may be attained through the employment of the exemplary embodiments of the invention which are illustrated in the accompanying drawings and which are described in detail hereinafter. Referring to the drawings:

Fig. 1 is a vertical sectional view of the upper end of the invention as installed in a well;

Fig. 2 is a downward continuation of Fig. 1;

Fig. 3 is a downward continuation of Fig. 2 and illustrates the lower end of the invention;

Figs. 4 and 5 are transverse sectional views respectively taken along the broken lines 44 and 5--5 of Fig. 2;

Fig. 6 is a transverse sectional view taken along the broken line 66 of Fig. 3;

Figs. 7 and 8 are vertical sectional views which are similar to Figs. 2 and 3, respectively, but which illustrate other operating positions for various components of the invention; and,

Figs. 9 and 10 are semidiagrammatic views illustrating the operation of the invention.

Referring particularly to Figs. 1 to 3, the numeral 11 designates a well casing set in a well bore 12 in la formation 13, the latter including a producing formation 14 containing well fluid. The Well fluid may, for example, include oil, gas, water and the like. In order to permit the well fluid to flow from the producing formation 14 into the Well bore 12, the lower end 15 of the well casing 11 is located above the upper surface of the producing formation and is cemented in to prevent communication between the producing formation and formations thereabove.

Disposed in the well casing 11 and extending downwardly below the lower end 15 thereof into that portion of the well bore 12 which is defined by the producing formation 14 is a liner or liner assembly 29 which is supported by the casing 11 through the medium of slips 21 in the usual manner and which carries packing means 22 providing a fluid-tight seal between the liner and the casing. The diameter of the liner 20 is somewhat less than that of the well bore 12 in the producing formation 14 so as to provide an annulus 23 therebetween, the function of the packing means 22 being to close the upper end of the annulus 23 so that well fluid from the producing formation may enter the interior of the liner only through a foraminous section 24 thereof. Referring particularly to Fig. 1, the liner 20 includes a tubular member 27 which is encompassed by the packing means 22, vertical movement of the packing means upwardly relative to the tubular member 27 being prevented by a collar 28 threaded onto the upper end of the tubular member 27. The collar 28 is internally threaded at its upper end to receive a tubing, such as a drill pipe, notshown, by means of which the liner 20 may be set in or removed from the well as is well known in the art. Below the packing means 22 and encompassing the tubular member 27 is a downwardly tapering collar 29 which engages complementarily tapered surfaces on the slips 21 so that the weight of the liner 2! acts through the tapered collar 29 to bias the slips into positive engagement with the well casing 11 to support the liner in the usual manner. The slips 21 are carried by spring arms 30 which are carried by an annular cage 31 encompassing the tubular member 27 and frictionally engaging the well casing 11. The cage 31 includes vertical strips of spring steel bent to provide a barrel-like shape for the cage and fastened top and bottom to collars slidably mounted on the member 27. The foregoing structure for supporting and sealing the liner relative to the casing comprises a hook-wall packer which, per se, is well known in the art and which is therefore only incompletely shown.

As shown in Fig. 2, the liner 20 includes a coupling 34 which is threaded onto the lower end of the tubular member 27 and which is provided with a passage 35 comprising a plurality of radial ports 36, the passage 35 providing fluid communication between the interior of the liner 20 and the annulus 23 at a point adjacent the upper end of the annulus. The coupling 34 is provided with an axial bore 37 therethrough which cooperates with a counterbore 38 therein to provide a tapered valve seat 39 for a tubular valve 40 which makes a sliding fit with the wall of the counterbore 38. The tubular valve 40 is threaded at its lower end, preferably with a left hand thread, into a second counterbore 41 in the coupling 34 so that rotation of the tubular valve in one direction causes it to advance upwardly into engagement with the valve seat 39 to close the passage 35. Rotation of the tubular valve 40 in the opposite direction causes it to retreat downwardly away from the valve seat 39 to open the passage 35. Leakage between the tubular valve 40 and the coupling 34 is prevented by an O-ring 42.

Referring particularly to Figs. 2 and 4, the tubular valve 40 is provided with a pair of inwardly extending, vertical ribs 45 which are adapted to be engaged by outwardly extending, vertical ribs 46 on a tubing 47 which, as will be discussed in more detail hereinafter, serves as a wash pipe. The wash pipe 47 extends downwardly from the surface of the ground and is insertable into the liner 20, the upper ends 48 of the ribs 45 and the lower ends 49 of the ribs 46 being tapered to facilitate insertion of the ribs 46 into the tubular valve 40. As will be apparent, if the wash pipe 47 is rotated at the surface of the ground, the ribs 46 thereon engage the ribs 45 on the tubular valve 40 to communicate such rotation of the wash pipe to the tubular valve, thereby causing it to advance toward or retreat from the valve seat 39 to close or open the passage 35, depending upon the direction of rotation of the wash pipe.

Referring particularly to Fig. 2, threaded into the. lower end of the coupling 34 is an inner casing 52 which is rendered foraminous throughout a substantial portion of its length, as by being provided-with vertical slots 53 therein. Encompassing and welded or otherwise secured to the inner casing 52 are vertically spaced rings 54, the ends of an outer casing 55 being welded or otherwise secured to the rings 54 to provide an annular space 5.6 between theinner and outer casings. The outer casing 55 is also rendered foraminous, as by being .provided with horizontal slots 57 therein. The annular space 56 between the inner and router casings 52 and 55 contains a gravel pack 58, the size of the particles of the gravel pack being dependent upon the size of the particles forming the producing formation 14, as is well known in the art. The foraminous portion of the inner casing 52, the outer casing 55 and the gravel pack 58 constitute a prepacked gravel liner and form the aforementioned foraminous section 24 of the liner 20.

Referring particularly to Fig. 3, the lower end of the inner ,casing 52 is threaded into a shoe .61 forming part of the liner or liner assembly 20, this shoe having a bore 62 therethroughand having at the upper end of the bore 62 a threaded counterbore 63 which cooperates with the bore 62 to define a shoulder 64. The lower end of the wash pipe 47 is adapted to be threadedly connected to the shoe 61, preferably by a left hand thread, in communication with the bore 62 therein by inserting the lower end of the wash pipe into the threaded ,counterbore 63 and simultaneously rotating the wash pipe at the surface of the ground, the upper end of the counterbore 63 being divergent, as indicated ,at 65, to guide the lower end of the wash pipe into the counterbore 63. Threaded insertion of the lower end of the wash pipe 47 into the counterbore 63 is limited by engagement of the lower end surface .of the wash pipe with the shoulder 64.

The bore 62 forms part of a passage 68 which communicates at one end with the annulus 23 adjacent the lower end thereof and which communicates at its other end with the wash pipe 47 when the latter is threadedly connected to the shoe 61. The passage 68 also includes the interior of an annular valve seat 69 which is clamped between an internal flange 70 on a collar 71 threaded onto the lower end of the shoe 61 and the upper end of a fitting 72 which is threaded into the collar 71. The fitting 72 is generally cup-shaped and is provided with a transverse wall 73 having ports 74 therethrough which also form part of the passage 68, the interior of the fitting 72 below the wall 73 communicating with the lower end of the annulus 23 through ports 75 which form further elements of the passage 68. To recapitulate, the passage 68 provides fluid communication between the lower end of the annulus 23 and the interior of the wash pipe 47 when the latter is threadedly connected to the shoe 61 and includes the bore 62, the interior of the collar 71, the interior of the annular valve seat 69, the interior of the fitting 72, and the ports 74 and 75.

The transverse wall 73 of the fitting 72 is provided with a central bore 78 therein which receives and serves as a guide for the stem 79 of a poppet valve 80, the latter being adapted to engage the annular valve seat 69 to close the passage 68 and being biased toward its closed position by a spring 81 seated at one end against the valve 80 and at its other end against the transverse wall 73. The poppet valve 30 is adapted to be moved toward its open position against the action of the spring 81 by an actuating element which consists of a stem 82 having a head 83 which is disposed within and secured to the lower end of the wash pipe 47. As .best shown in Fig. 6, the head 83 of the stem 82 comprises a plurality of radial arms 84 which are spaced apart circumferentially to provide fluid communication between the bore 62 of the passage .68 and the interior of the wash pipe.

As will be apparent, as the wash pipe 47 is threaded into the counterbore 63 in the shoe 61, the stem 82 opens the poppet valve to provide fluid communication between the lower end .of the annulus 2.3 and the interior of the wash pipe. Conversely, as the wash pipe is threadedly disconnected from the shoe 61, the spring 81 closes the poppet valve 80 to prevent fluid communication between the lower end of the annulus 23 and the interior of the wash pipe 47, or the interior of the liner 20.

The threaded connection between the tubular valve 40 and the coupling 34 is such that the tubular valve is moved toward its open position to open the passage 35 providing fluid communication between the upper end of the annulus 23 and the interior of the liner 20 as the wash pipe is threadedly connected to the shoe 61. Consequently, the tubular valve 40 is moved toward its closed position to close the passage 35 as the wash pipe 47 is disconnected from the shoe 61.

Thus, as the wash pipe 47 is threadedly connected to the shoe, it opens both the valves 40 and 80 and, as it is disconnected from the shoe, it closes both the valves 40 and .80, the position of the wash pipe when the valves 40 and 80 are open being shown in Figs. 2 and 3 and the position of the wash pipe just after closing the valves 48 and 80 being shownin Figs. 7 and 8. Thus, with this arrangement, both of the valves 40 and 80 are closed upon disconnection of the wash pipe from the shoe 61 to prevent fluid flow from the annulus 23 into the liner 2%] by way of the passages 35 and 68, thereby limiting such flow to the foraminous section 24 of the liner 20.

It will be understood that, as previously indicated, the annulus 23 between the producing formation 14 encompassing the well bore 12 and the liner 28 may be partially or completely filled with drilling mud when the liner 20 is set in the well. In order to bring the well in, i. e., to permit well fluid to flow from the producing formation 14into the annulus 23, it is necessary to remove at least substantially all of the drilling mud from the annulus 23, including any drilling mud that may be plastered on .the Wall of the well here at the level of the producing formation. In order to prevent reducing the permeability of the foraminous section 24 of the liner 20, an important feature of the invention is to exclude the drilling mud from the foramina of the foraminous section 24 during the operation of removing the drilling mud from the annulus 23. In accordance with the invention, this is accomplished by filling the foramina of the foraminous section 24 with a sealing material which is soluble in a predetermined solvent, but which is preferably insoluble in the drilling mud, i. e., in the vehicle carrying the drill ing mud, so that it will not be dissolved out to open the foramina to the drilling mud during the operation of removing the drilling mud from the annulus 23. The sealing material preferably closes substantially all of the interstices between the particles of the gravel pack 58 and may also close the slots or other forarnina in the inner and outer casings 52 and 55 of the forarninous section 24 of the liner 20. An important feature is that, since all of the interstices are substantially filled, a hydraulic balance is attained so that no pressure differential exists which would tend to cause the mud to enter the pack.

The nature of the sealing material employed to close the foramina of the foraminous section 24 depends upon the nature of the drilling mud vehicle, the fluid employed to remove the driling mud and the solvent employed to dissolve out the sealing material. Since the drilling mud vehicle and the fluid used to remove the drilling mud are ordinarily water, the sealing material is preferably .water insoluble, although if fluids other than water are employed for removing the drilling mud in particular, it is preferable that the sealing material be insoluble in such fluids also. t is convenient to rely upon the oil in the producing formation 14 to dissolve out the sealing material .after the drilling mud has been getnoved, in which Case it is necessary that the sealing material be oil soluble. However, as will be discussed in more detail hereinafter, other solvents may be employ'ed to dissolve out the sealing material, in which case it is necessary that the sealing material be soluble in such solvents. Examples of suitable oil soluble and water insoluble materials for closing the foramina of the foraminous section 24 of the liner 20 are natural asphalts, napthalenes, high melting point waxes, partially polymerized natural resins, asphaltic emulsions, sulphur, and the like.

Considering the operation of the invention, it will be assumed that the liner 2D has been set in the well in the position shown in the drawings with the foramina of the foraminous section 24 thereof closed by an appropriate sealing material. Subsequently, the wash pipe 47 is lowered into the well and the lower end thereof is threadedly connected to the shoe 61, thereby opening the valves 40 and 80 to provide fluid communication between the upper end of the annulus 23 and the interior of the liner through the passage 35 and to provide communication between the lower end of the annulus and the interior of the Wash pipe through the passage 68. Alternatively, the lower end of the Wash pipe 47 may be connected to the liner 20 on the surface prior to lowering the liner and the wash pipe into the well.

After the liner 20 has been set in the well and the wash pipe 47 has been connected thereto in the manner indicated, the drilling mud in the annulus 23 is washed therefrom by circulating washing fluid, which may be water, for example, vertically throughout substantially the entire length of the annulus from one of the passages 35 and 68 to the other. In Fig. 9, the flow of washing fluid is shown as being in the upward direction, the passage 68 in this instance serving as an inlet passage and the passage 35 serving as an outlet passage. Under the conditions illustrated in Fig. 9, the washing fluid flows downwardly through the wash pipe 47 and carries the drilling mud removed from the annulus 23 upwardly through the annular space between the wash pipe and the casing 11. Under the conditions illustrated in Fig. 10, the washing fluid flows downwardly through the annulus between the wash pipe and the casing 11 and enters the annulus 23 between the well bore 12 and the liner 20 through the passage 35, which in this instance serves as an inlet passage into the annulus 23. Consequently, under such conditions, the passage 68 serves as an outlet or discharge passage from the annulus 23 and the washing fluid, together with the drilling mud removed from the annulus 23 thereby, flows upwardly to the surface of the ground through the wash pipe 47.

It will be apparent that, by establishing a continuous flow of washing fluid throughout substantially the entire length of the annulus 23, it is possible to remove substantially all of the drilling mud from the annulus, which is an important feature of the invention. Such flow throughout substantially the entire vertical length of the annulus 23 is attainable because of the fact that the foramina of the foraminous section of the liner 20 are closed by the sealing material therein, which is an important feature. Also, as indicated previously, the sealing material in the foramina performs the additional function of preventing the entry of the drilling mud thereinto so that the drilling mud can in no way reduce the permeability of the foraminous section 24, which is another important feature.

It will be understood that the circulation of washing fluid through the annulus 23 is maintained for a suificien-t length of time to insure removal of substantially all of the drilling mud. Once the drilling mud has been removed from the annulus 23 to the desired extent, the circulation of washing fluid is terminated so that well fluid may fill the annulus 23, thereby permitting the oil in the well fluid to dissolve out the sealing material in the f-oramina of the foraminous section 24 in the event that an oil soluble sealing materi l is employed. Alternatively, suitable solvents in which the sealing material is soluble may be introduced into the annulus 23 and/ or the interior of the liner 20 to dissolve out the sealing material. If desired, such solvents may be circulated through the annulus in the manner hereinbefore indicated. In the event that selective opening of the liner is desired, such solvents may be applied locally to selected portions of the liner. This may be accomplished in various ways, as by packing off the selected portions, with a suitable packing means, not shown, inserted into the liner.

After the sealing material has been dissolved out of the foramina of the foraminous section 24 of the liner 20, or a portion thereof, the well fluid may flow therethrough from the annulus 23 into the interior of the liner in the usual manner. If the formation pressure is suflicient, the well may then be permitted to flow. Otherwise, a suitable pumping apparatus may be installed in the well.

It will be noted that, since disconnection of the wash pipe 47 automatically closes the valves 40 and 80, the well fluid can enter the interior of the liner only through the foramina of the foraminous section 24 thereof. This prevents the entry of sand into the interior of the liner through the passages 35 and 68, which is an important feature. It will be understood that the wash pipe 37 is removed after the solvent used to dissolve out the sealing material has been circulated if the sealing material is dissolved out by this method. Otherwise, the wash pipe may be removed upon completion of the operation of removing the drilling mud from the annulus 23.

It will be understood that although I have given examples of oil soluble and water insoluble sealing materials, I do not intend to be limited thereto since, as indicated above, sealing materials having various insolubility and solubility characteristics may be employed depending upon the natures of the drilling mud Vehicles, the washing fluid and the solvent employed. For example, it is possible to employ a sealing material which, while soluble in water, dissolves very slowly therein so that it serves to close the foramina of the foraminous section 24 of the liner 20 for a length of time suflicient to permit washing the drilling mud out of the annulus 23 with water, the water subsequently dissolving out the sealing material to open the foramina to flow of well fluid in the annulus 23 and to the interior of the liner. Various changes, modifications and substitutions may be incorporated in the particular embodiments disclosed without departing from the spirit of the invention and I hereby desire to be afforded the protection offered by the full scope of the appended claims.

I claim as my invention:

1. In a structure of the character described, the combination of: a liner including a foraminous intermediate section and having an inlet passage adjacent one end thereof and an outlet passage adjacent the other end thereof; an inlet valve means for opening and closing said inlet passage; an outlet valve means for opening and closing said outlet passage; a tubing insertable into said liner; means for threadedly connecting said tubing to said liner with said tubing in fluid communication with one of said passages; and means carried by said tubing for opening and closing said valve means in unison as said tubing is respectively threadedly connected to and disconnected from said liner.

2. The structure set forth in claim 1 wherein one of said valve means includes a reciprocable valve element which is engageable by an actuating element carried by said tubing and which is movable toward an open position by said actuating element as said tubing is threadedly connected to said liner, said one valve means including resilient means for biasing said valve element toward a closed position.

3. The structure set forth in claim 1 wherein one of said valve means includes a rotatable valve element which is threadedly connected to said liner and which is engageable by an actuating element carried by said tubing and which is movable toward an open position by said actuating element as said tubing is threadedly connected to said liner.

4. In a structure of the chaarcter described, the combination of: a casing set in a well; a liner disposed within said casing and extending downwardly below the lower end thereof, said liner having a foraminous intermediate section and being provided with an inlet passage adjacent one end thereof and an outlet passage adjacent the other end thereof; packing means carried by said liner above said inlet and outlet passages and engageable with said casing; 21 tubing insertable downwardly through said casing into said liner; means for threadedly connecting the lower end of said tubing to said liner with said tubing in fluid communication with one of said passages; and valve means actuable by elements on said tubing for opening said passages as said tubing is threadedly connected to said liner and for closing said passages as said tubing is threadedly disconnected from said liner.

References Cited in the file of this patent UNITED STATES PATENTS Benckenstein Aug. 19, Halliburton June 6, Layne et a1. Oct. 27, Reynolds July 9, Maloney Sept. 30, Layne Sept. 29, Knowlton May 4, Eckel Dec. 7, Wright Jan. 4, Eckel Mar. 13, Byrd May 1, Akeyson et a1. May 28, Byrd Apr. 22, Gray Jan. 10, 

1. IN A STRUCTURE OF THE CHARACTER DESCRIBED, THE COMBINATION OF: A LINER INCLUDING A FORAMINOUS INTERMEDIATE SECTION AND HAVING AN INLET PASSAGE ADJACENT ONE END THEREOF AND AN OUTLET PASSAGE ADJACENT THE OTHER END THEREOF; AN INLET VALVE MEANS FOR OPENING AND CLOSING SAID INLET PASSAGE; AN OUTLET VALVE MEANS FOR OPENING AND CLOSING SAID OUTLET PASSAGE; A TUBING INSERABLE INTO SAID LINER; MEANS FOR THREADEDLY CONNECTING SAID TUBING TO SAID LINER WITH SAID TUBING IN FLUID COMMUNICATION WITH 